Sub-quantity scales of the kind mentioned above are used to produce packaging or sale units of various products. In general, the principle of sub-quantity scales is that a continuously fed product stream is divided into sub-quantities and fed to a plurality of sub-quantity storage containers, then a weight of the sub-quantities is determined and finally a combination of multiple sub-quantities is selected to be filled into a packaging container in such a manner that the sub-quantity product weights add up to the desired packaging weight of the product.
The sub-quantity storage containers are filled by means of vibration conveyor devices, each of which has a conveying channel and is assigned to one of the sub-quantity storage containers. In particular when filling leaf salads it has been found that because of the high moisture content of the salad leaves, which pass from the product distributing device onto a conveying surface of the conveying channel, the salad leaves adhere to the conveying surface in an undesired manner in spite of the application of vibrations to the conveying channel, which means that an undisturbed vibration conveying of the leaf salads usually requires a drying process to precede the vibration conveying in order to arrive at a residual moisture that allows smooth vibration conveying in the conveying channel.
On the one hand, this leads to increased costs due to the additional drying process when packaging leaf salads, and on the other hand, the weight must often be reduced even to below admissible drained net weights of the filled product in order to allow a smooth packaging process. While this is to the benefit of the consumer, it constitutes a loss for the producer.